SRS Configuration for Network Positioning Accuracy
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Solution Overview
Problem
In 3GPP LTE wireless communication systems, network-based positioning using sounding reference signals (SRS) faces challenges due to SRS dropping, which is complex and often unknown to Location Measurement Units (LMUs, leading to performance degradation.
Innovation Solution
The eNodeB configures and schedules SRS parameters to reduce SRS dropping by proper configuration and scheduling, and sends a bitmap indicating dropped instances, while LMUs autonomously detect SRS dropping using cross-correlation techniques to ensure accurate timing measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the eNodeB transfers all SRS configuration data to LMUs, then measurement accuracy is improved, but signaling overhead and system complexity increase
Solution Approach 1:
The patent extracts only the essential SRS configuration parameters needed for timing measurements from the complete SRS configuration data. The eNodeB identifies and transfers specifically the parameters that LMUs require for accurate measurements, rather than transferring all configuration data. This selective extraction reduces signaling overhead while maintaining measurement accuracy.
Solution Approach 2:
The SRS configuration data is segmented into different categories: parameters essential for timing measurements (transferred to LMUs) and parameters not needed for positioning (retained by eNodeB). This segmentation allows the system to transfer only necessary information, reducing complexity while preserving measurement precision.
2Measurement precision
If the eNodeB transfers complete SRS configuration data to LMUs, then positioning accuracy is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts specifically the timing-critical SRS parameters from the complete configuration set. These extracted parameters include those necessary for timing advance calculation and SRS transmission timing, which are the only parameters LMUs need for positioning. This extraction minimizes signaling overhead while preserving positioning accuracy.
3Measurement precision
If LMUs attempt to measure all configured SRS transmissions, then measurement coverage is improved, but performance degrades due to SRS dropping
Solution Approach 1:
The patent applies preliminary action by having the eNodeB provide advance information about SRS transmission timing and configuration to LMUs before actual measurements occur. This allows LMUs to prepare for valid SRS transmissions and avoid attempting to measure dropped SRS instances, thereby maintaining measurement coverage while preventing performance degradation from invalid measurements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves positioning accuracy by reducing ineffective SRS measurements and avoids performance degradation, enabling precise UE location estimation.
Implementation Method 1
The time required for an uplink SRS signal transmitted by a UE to reach an LMU is proportional to the length of the transmission path between the UE and the LMU. Therefore, the LMU is able to calculate the UE's distance by uplink SRS timing measurements.
Data Source
AI summary
A method of network-based positioning using sounding reference signal (SRS) is proposed. An eNodeB configures a number of parameters of a periodic SRS transmission for a user equipment (UE). The eNodeB then transmits SRS configuration data for SRS measurements performed by a location measurement unit (LMU). The SRS configuration data includes cell-specific SRS bandwidth configuration and UE-specific SRS bandwidth configuration. The SRS configuration data may further include a number of antenna ports for SRS transmission, SRS frequency hopping bandwidth configuration, information on whether SRS sequence-group hopping is enabled, and ΔSS when SRS sequence hopping is enabled. Upon receiving the SRS configuration data, the LMU is able to perform timing measurements over the received SRS signals from the UE. In one embodiment, the LMU detects SRS dropping to avoid performance degradation of the network-based positioning.